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UNITED STATES PATENT QFFICE.

ROBERT GNEHM AND JAKOB SCHMID, OF BASLE, SlVITZERLAND, ASSIGNORS TO THE SOCIETY OF CHEMICAL INDUSTRY, OF SAME PLACE.

VIOLET COLORING MATTER.

STPECIFICATION forming part of Letters Patent No. 413,048, dated October15, 1889. Application filedllpril 5, 1888. $erial No. 269,711. (Specimens) Patented in France April 18, 1888,1lo. 190,067.

To aZZ whom it may concern':

Be it known that we, ROBERT GNEHM and J AICOB Somvnn, both citizens of Switzerland,

residing at Basic, Switzerland, have invented,

a new and useful Improvement in the Production of a Violet Coloring-Matter, (for which Letters Patent have been granted to us in France, No. 190,067, bearing date April 18, 1888,) of which the following is a specification.

This invention is based on the discovery that metaoxydiphenylamine, which has been first described by V. Merz and WV. \Neith, (Berichte der deutschen chemischen Gesellschaft, XIV,1881, page 2,3 l5,) when transformed into a phenylized derivation of meta amidophenolphthaleine, produces coloringmatters which have the same relation to the ordinary meta-amidophenolphthaleine as the rosaniline blue has to fuohsine.

The violet coloringanatter which forms the subject matter of this present application for a patent is produced by melting two molecules of metaoxydiphenylamine with one molecule of phthalio-acid anhydride in the presence of chloride of zinc or another condensing agent at a temperature of 100 to 170 centigrade.

In carrying out our invention we can proceed as follows: 5.5 kilograms of metaoxy- 3o diphenylamine, 2.5 kilograms of phthalic-acid anhydride, and 5.5 kilograms of chloride of zinc are intimately mixed and melted in an oil bath at a temperature of 160 to 170 centigrade, the heat being maintained for about two hours, when the reaction is terminated. The molten mass, which is at first semi-fluid, soon becomes solid. The glass-like melt,

which is of a bluish black color, is, when cold, finely pulverized and repeatedly boiled out 4.0 with diluted hydrochloric acid, diluted. soda lye, and water, and finally the ooloring matter is obtained in a pure state by extraction from alcohol.

The coloring matter itself is a powder of a glistening copper-like appearance, which may be designated monophenylmeta-amidophenolphthaleine. It dissolves in alcohol with a Violet-red color. It is insoluble in water, di luted acids, and alkalies, as Well as in bell zole and ligroine. It dissolves easily in hot so concentrated sulphuric acid and precipitates upon addition of cold water. lVhen zinc-dust and ammonia are added, the violet alcoholic solution becomes discolored. The original color is, however, restored by agitation with 5 5 water and air, or quicker when an oxidizing agent is added. It dyes silk a beautiful violet.

The dyes show a strong copperred fluores oence and are prominent by their consider able fastness to air and light.

The formula of our newooloring matter is as follows:

ROBERT GNEI-IM. [:L. s] JAKOB SOIIMID. [L. s] lVitnesses:

GEORGE GIFFORD,

N. I-InNzr. 

